The victims were in the "second line" -- the name for the informal street parades that regularly wind through New Orleans behind marching bands and dancers. The idiosyncratic local tradition has sometimes stirred debate in the city after shootings marred previous events.

"Just a very tragic day for us again in New Orleans, especially on Mother’s Day," Mayor Mitch Landrieu told reporters Sunday evening. “We have mothers that were shot, sisters that were shot, little children that were shot."

On Sunday, participants and onlookers were milling about on the streets and the sidewalks of east New Orleans' 7th Ward when shots rang out in quick succession at 1:47 p.m.

A video uploaded to social media after the shooting appeared to capture the sounds of at least two guns, which police confirmed.

Landrieu said there was no reason to believe the shooters were part of the procession.

Two participants told the Los Angeles Times that the second line, which featured music, drinking and dancing, had veered off its planned route right before the shooting.

“We were about 50 feet away from the actual shooting,” Happy Acee, 24, told The Times. “It sounded like there were six or seven shots that rang off, and we ended up hitting the deck. ... and literally people [were] just running over the top of us, just trying to get away."

“Right before it happened, there was some idiot on his trampoline on the left side [of the parade route], and everybody was looking at this fool" when the shooting began, Gretchen Ramke, 30, told The Times. “Somebody yelled, 'Everybody get down!' -- not the shooter -- and we hit the street, and I got bruised. I think somebody jumped on top of me."

Mary Beth Romig, a spokeswoman for the FBI in New Orleans, told the Associated Press that federal investigators have no indication that the shooting was an act of terrorism. “It's strictly an act of street violence in New Orleans,” she said.

A "full contingent" of officers had been accompanying the procession and saw three men running away from the scene that were deemed suspects, New Orleans police said in a statement.

Many of the wounded were grazed by bullets and ricochets, Remi Braden, spokesperson for the New Orleans Police Department, told The Times in a written statement.

"At this point, there are no fatalities, and most of the wounds are not life-threatening," Braden wrote. "But all medical conditions are not known at this time as victims were rushed to nearby hospitals. Detectives are conducting interviews, retrieving any surveillance video in the area and, of course, collecting all evidence."

"Me and Mom were going to the second line. I told her I didn't want to go because there are always shots at a second line," Tyler said. "And the second I heard shots, I heard shots fired, we ran outside and one man fell in my lap who had been shot." She said he'd been shot in his groin and hand.

Gambit, a New Orleans publication, reported that a noted local journalist, Deborah 'Big Red' Cotton, had been wounded in the shooting and was in guarded but stable condition at a hospital, where she underwent surgery.

Shootings have marred previous second-line parades throughout the city, to some controversy -- particularly for Cotton, who'd written about such violence before.

Three were wounded after a parade ended in 2006; another shooting occurred near a second-line parade in the 7th Ward in 2010 that left one woman dead. Cotton had written about one of the previous attacks and defended the second-line tradition, which dates to the 1800s.

"When you have a society that parades 40 weekends a year, there’s bound to be a murder that falls on the same day and possibly within the vicinity of the parade," Cotton wrote in Gambit in 2010.